China is stepping up pressure on Japan in a long-running maritime dispute, deploying Chinese vessels near contested East China Sea islands and accusing Japanese leaders of making provocative statements.

Japan said four Chinese coast guard patrol ships entered the disputed waters on Monday morning, prompting Japanese authorities to warn the vessels to leave the area, which they did a short time later.

Chinese ships have sailed near the islets on dozens of occasions in the past year. Such incidents typically end within several hours, with the Chinese vessels leaving the area after trading warnings and sovereignty claims with the Japanese.

Japan controls the disputed islands and calls them Senkaku, while China also claims sovereignty and refers to them as Daioyu.

Chinese Foreign Ministry spokeswoman Hua Chunying said Monday recent remarks by Japanese leaders about China are a "provocation." In unusually strong language, she accused Japanese politicians of being "pretentious."

Hua was speaking a day after Japan's Prime Minister Shinzo Abe told a group of Japanese troops that Tokyo will not tolerate "the use of force to change the region's status quo." His Sunday remarks were a reference to Japanese concerns about China's growing assertiveness in maritime disputes.

Hua said China believes that Japan "broke the status quo" of the East China Sea islands through unilateral actions. The Japanese government bought three of the uninhabited islets from their Japanese owners last year in a symbolic transfer of ownership that infuriated Beijing.

China also has reacted angrily to Japanese media reports that Prime Minister Abe recently approved a plan to shoot down foreign drones that ignore warnings to leave Japanese airspace.

Chinese Defense Ministry spokesman Geng Yansheng responded to those reports on Saturday, saying any such action by Japan would be a severe provocation to China and an "act of war."

Japan has scrambled fighter jets several times this year in response to Chinese military aircraft flying near Japanese airspace above Okinawa province, which incorporates the disputed islets.

Chinese foreign ministry spokeswoman Hua said the Chinese warplanes were conducting "normal exercises" in the East China Sea "in accordance with international law." She said "relevant parties need not make a fuss" about the operations.